Automatic draft regulator



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L. DANA AUTOMATI C DRAFT REGULATOR Filed Oct. 18, 1925 Patented Dec. 30,1924.

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LESLIE DANA, OF ST. LQUIS, MISSOURI.

AUTOMATIC DRAFT BEGULATGR.

Application filed October 18, 1923.

To all whom it may concern:

Be it known that I, LESLIE DANA, a citi- Zen of the United States, andresident of St. Louis, State of Missouri, have invented an Improvementin Automatic Draft Regulators, of which the following description, inconnection with the accompanying drawings, is a specification, likecharacters on the drawings representing like parts.

This invention pertains to automatic draft regulators for stoves, rangesand heating apparatus, more particularly for coal or other solid fuelburning apparatus for rooms, dwellings, and small buildings. The ivention aims to provide a relatively simple and reliable attachment forfuel burning apparatus of existing designs to regulate the draftautomatically in response to changes in the temperature of the heaterand of the room, both to economize in the consumption of fuel and alsoto prevent overheating of the apparatus and attendant liability ofcausing fire.

Other aims and advantages of my invention will appear in thespecification.

In the accompanying drawing, wherein l have shown one illustrativeembodiment.

of my invention;

Figure l is a side elevation of my improved automatic draft regulatorattached to an ordinary domestic heater;

Fig. 2 is a rear elevation of the same looking at it from the right ofFig. 1;

Fig. 3 is a sectional view taken on the line 33 of Fig. 2 and alsoshowing part of the heater in elevation; and

Fig. 4 is a perspective view of one of the thermostatic metal elements.

In the illustrative embodiment of my invention shown in the drawings, myimproved draft regulator is attached to the outlet fine of an ordinaryroom type heater 1 having a nipple 2 to which a collar 3 is secured inthe usual manner. The bevel joint between the collar and nipple may beground to make a as tight lit. The outlet end of the collar receives theusual smoke pipe 4.

A- check draft opening is preferably provided in the rear of the collarand a door 5 is hinged at its lower edge to swing outwardly to open andadmit air to the flue.

An operating rod or lever 6 is preferably secured to one slde of thedoor and has acrank 7 adapted to be engaged and opera Serial No.669,423.

ated by my in'iproved automatic control mechanism.

In order to operate the draft door automatically in response to changesin temperature of the heater casing and the room atmosphere afiacent theheater, a bending thermostat prc 'erably comprising a plurality of flat,flexible, bimetallic elements 8, each of which may advantageously bemade of copper and steel. strips A and B (Fig. 4) which have differentcoefficients of expansion under changes of temperature, cooper ates withthe crank arm 7 so as to permit the door to swing down freely due to itsown weight when the t mperature rises and causes the thermostaticelements to bend outwardly or rearwardly.

The thermostat is preferably, though not -ecessarily, enclosed andsecured at one end in a housing 9 having perforated side walls 10 one ofwhich is conveniently secured to the collar 3 and also Provides abearing for one hinge or pivot support of the door 5. The front and rearwalls or panels 11 and 12 are preferably perforated, and may be heldbetween ribs or shoulders 18 and lugs or ears let on the side panels(Figs. 2 and by suitable fastening means such, for example, as a bolt 15passing through the side panels. The front panel 11 preferably has aledge 16 (Fig. 3) on which the lower end of the thermostat is secured byany suitable means such as a bolt 17 passing through the front and rearwalls of the housing and through the bimetallic strips 8 (Fig. Thestrips may be held firmly seated in a channel on the ledge by a nut 18threaded on the bolt.

The copper side A (Fig. l) of the thermostat is exposed directly to theheat of the stove through the perforations in the front wall 11 of thehousing and contacts with an anti-friction roller 19 on the crank arm T,and, due to the greater coefficient of expansion of the copper than thatof the steel, when the temperature rises it will cause the upper end ofthe thermostat to bend rearwardly away from the crank arm '4" permittingthe door to swing downwardly to admit air into the flue and check thedraft. Upon a reduction in temperature the thermostat will straightenand swing inwardly toward the stove, operating the crank arm 7 to closethe door.

In order to counterbalance the weight of the door 5 when it is in openposition, and thereby l ssen the work required to operate the crank '7and permit the use of a lighter thermostatic element than wouldotherwise be required, a suitable counterweight 20 (Fig. 3) may beattached to the arm 6. This weight preferably extends substantiallyvertically downwardly below the arm when the door is in closed positionand swings toward the stove through an opening 2i in the adjacent wallof the housing (Fig.

The thermostat is preferablyadjustable sothat it may be set to permitthe door to open at a given temperature. I have shown a set screw 2threaded through the rear wall 12 of the housing and engaging the'thern'iostat near the lower end:- Iif it is desired to maintain a hightemperature, for

example, the set screw may be advanced to force the thermostat againstthe roller under pressure so that a greater distortion will be requiredto permit the crank 7 to begin to move. Also the setscrew may beadjusted in the opposite manner to cause the door to open at lowertemperatures.

' I While I have illustrated my improved draft regulator as beingapplied to a reversible collar on an ordinary heater, it will beapparent that it is equally applicable to other types of heaters and tovarious other parts thereof. 7

' Obviously, my invention is not limited to the details ofconstructionherein described and shown in the drawings, but is susceptible ofvarious changes and modifications.

Having thus described one illustrative em bodiment of my invention andwithout limiting myself thereto, what I claim and desire to secure byLetters Patent'is:

1. An automatic draft regulator for stoves, furnaces and the likecomprising, in combination. a draft door on the outlet flue, said doorbeing vertically disposed and pivoted at its lower edge to swingoutwards at the top, a crank arm on saiddoor and a bending thermostatoutside said flue 00- operating with said arm to permit said door 'toopen and cause it to close upon a rise and tall, respectively, in' thetemperature of the stove.

2. An automatic draft regulator for stoves, furnaces and the likecomprising, in combination, a draft door on the outlet flue pivoted toswing open under the action of V gravity, said door having a crankarm'thereon provided with anantitriction roller at its ends, and abending thermostat having its free, end engaging with said roller tohold said door closed normally and to cause 1t 7 to open and close upona rise and fall, re-

spectively, in the temperature of the stove.

3. In a check draft regulator for stoves. furnaces and, the like, avertically disposed check draft door hinged at its lower side to swingoutwards to open, and a bending thermostat secured beneath said doorandcooperating with said door to'hold it in closed position under normaltemperature conditions and adapted to permit it to open byfgravity underexcessive temperature conditions, said thermostat being adjustable atits lower end whereby to change the'temperature at which it respondssufliciently to permit the door to open. 1

V In a heater, the combination of a collar secured to the outlet flue, asubstantially verticalcheck draft door hinged'at its lower side on ,saidcollar to swing outwards, and heat controlled operating meanscooperating with said door comprising a housing supbi-metallic bending Vthermostat mounted in said housing and having its side of greaterexpansibility arranged adjacent said collar and exposed directly to heatradiating from the flue, whereby an increase in temperature of said fluecauses said. thermostat element to bend away from said flue and causesaid door to swingopen.

6. An automatic lcheck draft regulator orted on said collar outside saidflue a p i element comprising, in combination, a vertically disposeddoor hinged at its lower side and tending to sw ng open by gravity,means for holding said door in closed position under normal temperatureconditions and permit ting it to open under predetermined temperatureconditions, and a counterwelght for said door disposed below. its hingepivot axis and adapted to aid said means in returning it to closedposition atter it has opened and the temperature falls below saidpredetermined amount.

7. An automatic draft regulator for stoves, furnaces and the like,comprising, in combination, a collar secured'to the outlet flue having adraft opening in an exposed wall, a draft door adapted to close saidopening and having one edge mounted in a pivot bearing on the wall ofsaid collar, a perforated housing providing a second bearing for saiddoor and secured to the collar at one side of said opening, andaflexible thermostat secured at one end in said housing and with itsfree'end cooperating with said door to cause it to open and close underthe influence of temperature conditions adjacent the heater.

' 8. An automatic draft regulator comprising, in combination, the collar3 supporting with said crank arm to cause the door to open and closeunder the influence o't changes 1n surrounding temperature conditions,all sub- 10 stentielly as shown and deseribed.

In testimony whereof, I have signed my name to this specification.

LESLIE DANA.

